Definition
A fire-warning sensor that triggers an alarm when the temperature in a monitored area climbs faster than a preset rate, rather than when it simply exceeds a fixed temperature. It detects the speed of heating, so a rapidly developing fire is reported even before the area reaches a high absolute temperature.
Plain English
A fire detector that watches how fast the temperature is going up. If the heat rises quickly, it sounds the warning, even if the area isn't very hot yet.
Context Anchor
Seen in aircraft fire-detection systems for engine compartments, heater areas, cargo areas, or auxiliary power unit compartments.
Derivation
The name describes exactly how it works: it responds to the rate (speed) at which temperature rises. Knowing this helps separate it from a fixed-temperature detector, which only responds when a set temperature is reached.
Why Pilots Care
Provides earlier warning of developing fires than fixed-temperature detectors, allowing more time for shutdown or extinguishing actions.
Grounding Statement
The key idea is speed of heating: a fast temperature climb can be a fire warning even before the area is extremely hot.
Intuition Check
Do not read this as a detector that only reacts to a certain temperature. It reacts to the rate of increase — how fast the temperature is rising.
Example Sentence 1
The engine fire warning came from a rate-of-temperature-rise fire detector mounted in the nacelle.
Example Sentence 2
After landing, the crew inspected the rate-of-temperature-rise fire detector wiring as part of the post-flight check.